Method for production of hydrocarbons from organic-rich rock

Abstract

A method for accelerating the conversion of kerogen to hydrocarbons in a subterranean formation containing organic-rich rock that is located in the vicinity of reservoir-quality strata. Sufficient heat is generated in the reservoir-quality strata such that it heats the organic-rich rock in the subterranean formation and accelerates the conversion of kerogen to hydrocarbons in the formation.

Description

CROSS-REFERENCE[0001]This application claims the benefit of U.S. Provisional Application No. 60 / 198,301 filed Apr. 19, 2000.FIELD OF THE INVENTION[0002]This invention relates to the production of hydrocarbons from organic-rich rock such as kerogen-bearing, subterranean shale formations. More specifically, the invention relates to using reservoir quality strata as a heat source for conversion of the kerogen to hydrocarbons.BACKGROUND OF THE INTENTION[0003]Ever since the commercial use and production of liquid hydrocarbons commenced in the mid-19th century, scientists have pursued ways of economically extracting hydrocarbons from organic-rich rocks such as oil shale. Historically and currently, almost all hydrocarbons are produced from subterranean reservoir strata and formations. Such hydrocarbon-bearing reservoirs, containing natural gas and / or oil, typically comprise permeable and porous rock such as sandstone or limestone (carbonate). Frequently, these types of rocks serve as trap...

AI Technical Summary

Benefits of technology

[0015]In one embodiment of the invention, a reservoir formation containing hydrocarbons is located in the vicinity of a kerogen-bearing subterranean formation, preferably underlying the kerogen-bearing formation. An oxygen-bearing gas, such as air, is injected into the reservoir and is combusted with the hydrocarbons in the reservoir. The combustion process generates heat within the reservoir which is transferred to the kerogen-bearing formation and raises the temperature within a portion of the formation to at least about 220° C. and, preferably, to at least about 250° C. The generated heat accelerates the conversion of the kerogen to hydrocarbons and, at the temperatures indicated above, conversion will take place at a commercially acceptable level.

Problems solved by technology

This process is extremely slow and takes place over geologic time.

These immature source rocks, however, contain the overwhelming majority of buried organic matter in the earth's crust.

Unfortunately, kerogen is not readily liberated from shale or other source rocks.

A more current project is the Stuart Oil Shale Project in Australia which uses a rotating retort to heat the shale to 500° C. There are a number of drawbacks to surface production of shale oil which has made its production more costly compared to conventional hydrocarbon production.

These drawbacks include the high costs of mining, crushing, and retorting the shale and the environmental cost of shale rubble disposal, site remediation, and clean operation of the retort and associated plant.

As with other in situ oil shale retorts, the shale rubblization involved in this process limits it to very shallow depths.

This process is very difficult to manage because it requires a controlled flow of the extracting fluid through the oil shale.

However, with this method, spacing of the wells is extremely close and many wells would be required to achieve commercial production volumes of hydrocarbons.

Overall, the various in situ processes for producing oil shale have been commercially unattractive.

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